General Left System Centre System Right System PTU RAT Schematics EICAS Messages

RAT (Dual Engine Failure) Show Schematic only

Restart Left Engine Restart Right Engine Leak from Left System Leak from Centre System Leak from Right System Power Transfer Unit (operates if Left engine failed or Left EDP pressure low) Reserve brakes Ram Air Turbine (automatically operates when both engines have failed) Ram Air Turbine Manual Deployment Switch Alternate Brakes Left Thrust Reverser Rudder Ratio Landing Gear - Normal System Operation Spoilers Yaw Dampers Ailerons ETOPS equiped aircraft only Flaps and Slats - Normal System Operation Nosewheel Steering Elevators Spoilers Rudder Elevator Feel Stabilizer Ailerons Normal Brakes Right Thrust Reverser Power Transfer Unit Spoilers
Ram Air Turbine (RAT) Pump

Ram Air Turbine The Ram Air Turbine (RAT) hydraulic pump is located in the body fairing aft of the right wing landing gear.

When deployed, The RAT provides hydraulic power to the flight controls portion of the Centre Hydraulic System. The RAT provides adequate hydraulic power at speeds above 130 knots. Inflight (Air/Ground System in the air mode and airspeed > 80 kts), the RAT deploys automatically when both engines fail (N3 < 45% rpm) - signalled by the speed cards.

Ram Air Turbine switchThe RAT can be deployed manually by pushing the RAM AIR TURBINE switch. The UNLKD light illuminates and the EICAS advisory message RAT UNLOCKED displays when the RAT is not stowed and locked. When the RAT is producing pressure the Ram Air Turbine PRESS light illuminates. Once deployed, the RAT cannot be stowed in flight.

Pressure produced by the ram air turbine is isolated from the system pressure sensor. Therefore, the SYS PRESS light remains illuminated if the RAT is the only source of centre system pressure.

Note: Powered by the Hot Battery Bus, the Ram Air Turbine switch is live at all times.

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